1. Field of the Invention
This invention is related to an improved method of manufacturing blades for scissors.
2. Description of the Prior Art
Referring to FIGS. 4, 5 and 6, the conventional scissors are generally made of steel so that they are heavy and difficult to be operated especially for those with larger sizes. Recently, there is an increasing need for safety scissors for home work and office work and so it has long been desired to develop a kind of scissors which are sharp, lightweight and durable in use. Hence, scissors with plastic handles and steel blades have been designed to meet this need. As shown in FIGS. 4, 5 and 6, such scissors have handles 21 made by injection moulding, blades 22 made of plastic, and L-shaped metal cutters 23 made by pressing. The blade 22 is provided with protuberances 25 adapted to engage with the holes 24 of the cutters 23 and fixedly secured thereto by ultrasonic bonding thereby providing the blade 22 with a metal cutter 23. However, the cutter 23 is made from a sheet of metal by pressing and so the thickness of the cutter 23 is limited by the press and usually below 1 mm thereby making it impossible to do heavy-duty cutting works and therefore limiting its usage.
The metal cutter 23 is only kept in place by the two protuberances 25 so that the stress is concentrated at the two protuberances 25 in use thereby easily loosening the metal cutter 23 and even breaking protuberances 25 and therefore making the scissors unfit for use anymore. Of more importance is the fact that the clearance A between the curved edge of the metal cutter 23 and the blade 22 is very difficult to be cleaned. In addition, the metal cutter is comparatively thin and it is difficult and unfit to be ground so that once it becomes blunt, it will be of no use and has to be discarded.
Therefore, it is an object of the present invention to provide an improved method of manufacturing blades for scissors which obviate and mitigate the above-mentioned drawbacks.